Air flow controller for electrical equipment holder

ABSTRACT

A fan is controlled to remove or provide air from or to an equipment enclosure as a function of a difference in pressure between a front and back of a rack of equipment.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application Ser. No. 61/051,952, filed May 9, 2008, and entitled “AIR FLOW CONTROLLER FOR ELECTRICAL EQUIPMENT HOLDER,” which is incorporated herein by reference in its entirety.

BACKGROUND

Many computer components and electrical devices are designed with cooling mechanisms, such as fans. Airflow capacity of the fans may be designed to cool the component or device in an open environment. However, many times such components and devices may be stacked or otherwise arranged in equipment holders, such as racks with front and back panels. Placing the equipment or components in such holders may create an environment where the fans in the individual components and devices do not provide adequate ventilation.

In some prior devices, temperature within the enclosure is measured, and used to control a fan that evacuates air from the enclosure to maintain a desired temperature range within the enclosure. Airflow may also be measured and controlled in further prior devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system for controlling airflow as a function of differential pressure in an equipment enclosure according to an example embodiment.

FIG. 2 is a block schematic diagram of an alternative system for controlling airflow according to an example embodiment.

FIG. 3 is a block schematic diagram of an alternative system for controlling airflow according to an example embodiment.

FIG. 4 is a block schematic diagram of an alternative system for controlling airflow according to an example embodiment.

FIG. 5 is a block schematic diagram of computer system operable as a controller according to an example embodiment.

FIG. 6 is a block schematic diagram of an alternative system for controlling airflow according to an example embodiment.

FIG. 7 is a block schematic diagram of a further alternative system for controlling airflow according to an example embodiment.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural, logical and electrical changes may be made without departing from the scope of the present invention. The following description of example embodiments is, therefore, not to be taken in a limited sense, and the scope of the present invention is defined by the appended claims.

The functions or algorithms described herein may be implemented in software or a combination of software and human implemented procedures in one embodiment. The software may consist of computer executable instructions stored on computer readable media such as memory or other type of storage devices. Further, such functions correspond to modules, which are software, hardware, firmware or any combination thereof. Multiple functions may be performed in one or more modules as desired, and the embodiments described are merely examples. The software may be executed on a digital signal processor, ASIC, microprocessor, or other type of processor operating on a computer system, such as a personal computer, server or other computer system.

Multiple embodiments of a system and method for controlling a fan in an equipment enclosure as a function of differential pressure between two sides of the equipment enclosures are described. In some embodiments, air is removed from a back of the enclosure to equalize the pressure. Multiple pressure measurements may be used, and multiple fans may be controlled in various embodiments.

In FIG. 1, a system 100 includes an equipment enclosure 110. Equipment enclosure 110 may have supports 115 for supporting one more pieces of equipment 120. The supported equipment may be referred to as a rack of equipment. One or more of such pieces of equipment may have a fan for cooling itself. A differential pressure sensor 125 is supported by the enclosure 110, and is operable to sense a first pressure at a first side 130 of the rack in equipment enclosure 110 and a second pressure at a second side 135 of the rack in equipment enclosure 110. The differential pressure sensor may provide a signal representing a difference between the first and second pressure. In one embodiment, wireless absolute pressure sensors 140, 141 are used to sense the first and second pressures.

A fan 145 is supported by the equipment enclosure 110 and is operable to remove air from the second side 135 of the equipment enclosure 110. A controller 150 is coupled to the fan 145 and receives the signal from the differential pressure sensor 125 or sensors 140, 141, or both. Controller 150 controls the fan about a differential pressure set point, such as zero in one embodiment to provide an environment for the equipment 120 that is similar to that for which it is designed, such as where equipment 120 is free standing and not supported within an equipment enclosure.

In one embodiment, controller 150 may be a PID controller, controlling the fan to keep the differential pressure about a predetermined or pre selected set point, such as zero in one embodiment. Other set points may be used, to create a decrease in pressure if desired to allow cooling mechanisms in the equipment to operate at reduced levels or just provide more effective cooling. A range of set points may also be utilized to control the difference in pressure, such as plus or minus 0.1 atmospheres about a set point which may be zero in one embodiment.

In one embodiment, the first side 130 of the equipment enclosure 110 corresponds to front side of the equipment enclosure 110 and the second side 135 of the equipment enclosure corresponds to a back side of the equipment enclosure 110. In some embodiments, the front side is an air intake side, and the back side is and air exhaust side.

The pieces of equipment 120 may be supported within the enclosure such that air moves through them generally from the front of the enclosure to the back of the enclosure. In further embodiments, different pieces of equipment 120 may be mounted such that their airflow direction alternates at adjacent pieces of equipment 120, or may be mounted without regard to their airflow direction. In still further embodiments, only one side of the equipment rack may be enclosed. The pressure difference may then be measured between the side of the equipment rack that is enclosed, and the side that is not. Air may be exhausted or provided to the enclosure in some embodiments.

FIG. 2 is a block schematic diagram illustrating an alternative pressure sensing arrangement. The numbering is consistent with FIG. 1. In one embodiment, pressure sensor 125 is a capacitive differential pressure sensor, with a first pressure from a tube 210 having an opening 215 providing a pressure from the first side 130 of enclosure 110. A second pressure is provided by a second tube 220 having an opening 225 proximate the second side 135 of enclosure 110. The tubes may be supported many different ways within the enclosure, or even on the outside of the enclosure if desired. The openings 215 and 225 may be placed to conduct the pressures corresponding closest to the pressures encountered by the equipment 120 to either side of a capacitive diaphragm within the pressure sensor 125. In some embodiments, the openings are not placed in areas of high air velocity, as such a placement could affect the pressure encountered. In further embodiments, any type of differential pressure sensor may be used.

FIG. 3 is a block schematic diagram illustrating a further embodiment 300 where the pressure sensor 125 is provided an average pressure from multiple openings 310, 315, 320 about the first side 130 of the enclosure 110, and from multiple openings 325, 330, 335 about the second side 125 of the enclosure 110. In this embodiment, such pressure readings are somewhat averaged by the connection of multiple tubes to the differential pressure sensor 125. The tubes are shown as connecting at some distance from the differential pressure sensor 125, which may not result in a true average of the pressure. In further embodiments, completely separate tubes joining at the differential pressure sensor 125 may be used to obtain an even closer average of the pressures.

FIG. 4 is a block schematic diagram illustrating a further embodiment 400, where multiple fans 410, 415, 420 are used with independent pressure measurements. A combined differential pressure sensor and controller 425, 430 and 435 are used to control each corresponding fan. Differential pressure sensor and controller 425 has tubes 440 and 442 positioned to provide differential pressure from the first side 130 and second side 135 proximate one piece of equipment 444. Fan 410 is then controlled by controller 425 based on differential pressure between first and second side of equipment 444. Fan 410 is positioned adjacent equipment 444 in order to more directly lower pressure at the second side of equipment 444, and have less effect regarding other equipment in the enclosure.

Similarly, differential pressure sensor and controller 430 has tubes 450 and 452 positioned to provide differential pressure from the first side 130 and second side 135 proximate one piece of equipment 454. Fan 415 is then controlled by controller 430 based on differential pressure between first and second side of equipment 454. Fan 415 is positioned adjacent equipment 454 in order to more directly lower pressure at the second side of equipment 454, and have less effect regarding other equipment in the enclosure.

Similarly, differential pressure sensor and controller 435 has tubes 460 and 462 positioned to provide differential pressure from the first side 130 and second side 135 proximate one piece of equipment 464. Fan 420 is then controlled by controller 435 based on differential pressure between first and second side of equipment 464. Fan 420 is positioned adjacent equipment 464 in order to more directly lower pressure at the second side of equipment 464, and have less effect regarding other equipment in the enclosure. Further fans and controllers may be provided for additional equipment. In further embodiments, two fans and controllers may be used for multiple pieces of equipment without a one to one correspondence. The multiple fans may be controlled as a function of one or more differential pressure measurements.

In various embodiments, the controller may be a general programmed computing device as shown in FIG. 5 or a dedicated controller implementing one or more forms of PID control or other control as desired to operate the fans to a desired set point. In one embodiment, a computer 510, may include a processing unit 502, memory 504, removable storage 512, and non-removable storage 514. Memory 504 may include volatile memory 506 and non-volatile memory 508. Computer 510 may include—or have access to a computing environment that includes—a variety of computer-readable media, such as volatile memory 506 and non-volatile memory 508, removable storage 512 and non-removable storage 514. Computer storage includes random access memory (RAM), read only memory (ROM), erasable programmable read-only memory (EPROM) & electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD ROM), Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other physical medium capable of storing computer-readable instructions. Computer 510 may include or have access to a computing environment that includes input 516, output 518, and a communication connection 520. The computer may operate in a networked environment using a communication connection to connect to one or more remote computers. The remote computer may include a personal computer (PC), server, router, network PC, a peer device or other common network node, or the like. The communication connection may include a Local Area Network (LAN), a Wide Area Network (WAN) or other networks.

Computer-readable instructions stored on a computer-readable medium are executable by the processing unit 502 of the computer 510. A hard drive, CD-ROM, and RAM are some examples of articles including a computer-readable medium. For a controller application, many of the above components may not be needed, and the controller may be implemented without storage devices and various other components not needed to control a fan.

A block schematic diagram of a further embodiment is shown in FIG. 6 generally at 600. Electrical equivalent of airflow and pressure in a frame is shown where equipment pressure difference is controlled to a zero point at 610. An internal fan 620, referred to as Fan_Eqpt is the internal fan for a piece of equipment that is designed to offer adequate airflow at zero pressure difference. A frame fan 630 is disposed in a frame 640 and referred to as the Fan_Frame. This fan is varied to keep ΔP=0. The pressure drop due to series resistance from front door or rear structure is eliminated by fan 640.

In still a further embodiment as illustrated in block cross section form in FIG. 7, equipment may be supported within one or more rows of racks. Two such rows of racks 710, 715 are shown in FIG. 7 supported by a raised floor 720. A closed aisle 725 is formed between the racks 710 and 715 by including a top 730 and sides, one of which is visible at 735.

A fan assisted floor tile 740 contains multiple fans that provide cooling air to the rows of racks from the floor. Without the fans, airflow through the equipment in the racks may be severely reduced due to a high effective flow impedance of the racks. In one embodiment, the fan assisted floor tile is located in the raised floor 720 and disposed directly between the rows of racks 710, 715 to provide airflow through a grate in the floor.

A differential pressure sensor 745 is disposed to sense a difference in pressure between the rows of racks in the aisle 715 and ambient, where equipment may exhaust air. The pressure sensor 745 is coupled to a controller 750, which in turn is coupled to control the fan assisted floor tile 740 to provide a desired difference in pressure as described above. Thus, the difference in pressure from one side of a rack and another side of the rack is sensed and used to control fans providing cooling airflow to the enclosure. In this case, a first side of the rack corresponds to the aisle, or an equipment enclosure, while a second side of the rack is outside the enclosure. In still further embodiments, only one rack is provided, with the second rack replaced with a wall to provide enclosure of the aisle.

In the embodiment described above, closed aisle 725 is a cold aisle. In further embodiments, closed aisle 725 may be a hot aisle, with the fan assisted floor tile 740 disposed on the top 735 of the aisle, and pulling hot air form the aisle out of the aisle. No raised floor is needed in this embodiment, and cool air from outside the racks may be drawn in through the racks to cool them. The pressure sensing and fan control may be controlled in a similar manner as a function of the difference in pressure.

The Abstract is provided to comply with 37 C.F.R. §1.72(b) to allow the reader to quickly ascertain the nature and gist of the technical disclosure. The Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 

1. A method comprising: measuring a difference in air pressure between a first side of an equipment enclosure and a second side of the equipment enclosure, wherein some equipment mounted in the enclosure has self contained cooling mechanisms that cool based on convection; and controlling the measured differential air pressure about a desired set point.
 2. The method of claim 1 wherein the set point is zero.
 3. The method of claim 1 wherein the difference in air pressure is measured by a differential pressure sensor having two tubes, a first tube having an opening positioned near the first side of the equipment enclosure and a second tube having an opening positioned near the second side of the equipment enclosure.
 4. The method of claim 3 wherein at least one of the tubes comprises multiple tubes with opening positioned at different places to provide an average of the pressure at the first or second side of the enclosure.
 5. The method of claim 1 wherein the differential air pressure is controlled by using a fan to remove air from the second side of the equipment enclosure.
 6. The method of claim 1 wherein the differential air pressure is controlled by using multiple fans to remove air from the second side of the equipment enclosure.
 7. The method of claim 6 wherein multiple fans are controlled as a function of measured difference in pressure between the first side of the enclosure and a corresponding point proximate each fan.
 8. The method of claim 1 wherein the difference in air pressure is measured as a function of air pressure at multiple points in the first and second sides of the equipment enclosure.
 9. The method of claim 1 wherein multiple wireless absolute pressure sensors are used to sense the difference in pressure.
 10. The method of claim 1 wherein the first side of the equipment enclosure corresponds to front side of the equipment enclosure and the second side of the equipment enclosure corresponds to a back side of the equipment enclosure.
 11. The method of claim 1 wherein the equipment enclosure comprises a two rows of racks of equipment having an enclosed aisle between the two rows of racks, and wherein the differential air pressure is controlled by using a fan to provide air to the enclosed aisle.
 12. A device comprising: a differential pressure sensor operable to sense a first pressure at a first side of an equipment rack in an enclosure and a second pressure at a second side of the equipment rack and provide a signal representing a difference between the first and second pressures; a fan operable to add or remove air from the equipment enclosure; and a controller coupled to the fan for receiving the signal from the differential pressure sensor and controlling the fan about a differential pressure set point.
 13. The device of claim 12 wherein the first side of the equipment rack corresponds to a front side of the equipment enclosure.
 14. A system comprising: an equipment enclosure; multiple pieces of equipment, each having a fan for cooling itself; a differential pressure sensor operable to sense a first pressure at a first side of an equipment enclosure and a second pressure at a second side of the equipment enclosure and provide a signal representing a difference between the first and second pressure; a fan supported by the equipment enclosure and operable to remove air from the second side of the equipment enclosure; and a controller coupled to the fan for receiving the signal from the differential pressure sensor and controlling the fan about a differential pressure set point.
 15. The system of claim 14 wherein the first side of the equipment enclosure corresponds to front side of the equipment enclosure and the second side of the equipment enclosure corresponds to a back side of the equipment enclosure.
 16. The system of claim 15 wherein the pieces of equipment are supported within the enclosure such that air moves through them generally from the front of the enclosure to the back of the enclosure.
 17. The system of claim 14 wherein the differential pressure set point is zero.
 18. A system comprising: a differential pressure sensor operable to sense a first pressure within an enclosed aisle separating two rows of racks of equipment and a second pressure at a side of one of the rows of racks opposite the enclosed aisle and provide a signal representing a difference between the first and second pressures; a fan operable to provide air to the enclosed aisle or remove air from the enclosed aisle separating the rows of racks of equipment; and a controller coupled to the fan for receiving the signal from the differential pressure sensor and controlling the fan about a differential pressure set point.
 19. The system of claim 18 wherein the fan comprises a fan assisted floor tile.
 20. The system of claim 18 wherein at least one of the equipment has a fan to cool itself. 